1. Field of the Invention
The present invention relates to a ceramic separation membrane and a dehydration method, and more particularly, it relates to a ceramic separation membrane in which durability and a separation property is enhanced, and a dehydration method in which this ceramic separation membrane is used.
2. Description of Related Art
Heretofore, to separate a specific component from a mixture of gases or liquids containing an organic material, various methods have been employed in accordance with properties of a substance which is an object of separation. Examples of the various methods include a distillation method, an azeotropic distillation method, a solvent extraction/distillation method, and a separation method by an adsorbent. However, these methods have the problems that a lot of energy is required and that an application range of the separation object is restrictive.
In recent years, as a method replacing the above separation methods, there has been suggested a membrane separation method in which a membrane such as a polymer membrane is used (see Patent Document 1). Examples of the polymer membrane include a carbon membrane and a hollow fiber membrane. This polymer membrane has excellent processing properties. However, the polymer membrane has a problem that a heat resistance is low. Furthermore, the polymer membrane has a low resistance to chemicals, and particularly, the polymer membrane comes in contact with an organic material such as an organic solvent or an organic acid to swell in many cases. Consequently, there has been the problem that the application range of the separation object is restrictive.
On the other hand, there has also been suggested a membrane separation method in which a separation membrane (a ceramic separation membrane) having an inorganic material as in a zeolite membrane or the like is used (see Patent Documents 2 to 5). As to the zeolite membrane, for example, a mixture (an acidic aqueous solution) of an organic material (an acid component such as acetic acid) and water is passed through this zeolite membrane, thereby allowing water to selectively permeate the membrane, so that the water can be removed from the acidic aqueous solution. In other words, when the zeolite membrane is used, the acidic aqueous solution can be concentrated. In such a membrane separation method in which the separation membrane having the inorganic material is used, an amount of the energy to be used can be reduced as compared with the above separation method by the distillation or the adsorbent. Furthermore, the separation can be performed in a broader temperature range than in the polymer membrane.